M-shiki Princess

From Aerandria Scans:

Kanako is an unattractive and not very capable office lady, until the day her mother passes away and she turns out to be the sole heiress of the old and elite Kinaga house. So suddenly, Kanako has not only to uphold her duties as an heiress, but to turn into an attractive lady so that she can marry accordingly to her new status. Thanks to the family butler and her own efforts, she manages somehow, but even in the middle of her newfound glamor, her world still continues to revolve around her butler…